Bitcoin Fields Its First Quantum-Safe Transaction

A quantum-safe transaction has been mined on the Bitcoin mainnet for the first time ever.

The underlying effort, fashioned around a April 2026 research paper by StarkWare's Avihu Levy, turned Bitcoin's Script rules into a puzzle that Shor's algorithm, the quantum method that can break elliptic curve cryptography, can't solve.

What's the Scoop?

• The trick: Quantum-Safe Bitcoin (QSB) buries a second, hash-based lock inside the spending script. Rather than trusting the secrecy of a private key, it hashes a transaction-bound public key with RIPEMD-160 and checks whether the result happens to look like a valid ECDSA signature (something only about 1 in 2^46 random keys will do). Finding that needle, not knowing a private key, is what authorizes the spend.
• Prior work: The design builds on Robin Linus's Binohash and a 2024 method from Ethan Heilman for smuggling Lamport signatures into Bitcoin Script without OP_CAT. QSB swaps out Binohash's ECDSA-dependent proof-of-work for one that leans purely on hash pre-image resistance, sealing the exact gap Shor's algorithm would otherwise exploit.
• The mining: The finished transaction blows past Bitcoin's standard relay-policy limits, so it couldn't just wait around in the mempool. StarkWare's Tomer Giladi carried the implementation to completion, and MARA's Slipstream service (built specifically for non-standard transactions like this one) delivered it straight to a miner.
• The price tag: Brute-forcing the right transaction parameters ran roughly $75-$150 in GPU time, per the project's GitHub repo, a cost that would fall further the more GPUs get thrown at the search.
• Not the final word: Levy downplayed the milestone himself, calling QSB "a research quirk and not the straightforward way for Bitcoin to become" quantum-safe. StarkWare CEO Eli Ben-Sasson was more triumphant, writing that the result shows "Bitcoin has no expiration date."